The disclosure relates to a method for providing a clamping force generated by an automatic parking brake, to a controller or regulator, and to an automatic parking brake.
DE 10 2011 005 842 A1 discloses an automatic parking brake for use in a vehicle, which can exert a clamping force on a brake disk in order to immobilize a stationary vehicle. The clamping force is generated by a spindle nut and brake piston which are moved by a brake motor and clamp the brake disk between two brake pads during an application process. The brake piston can also be pressurized with a hydraulic brake fluid, which is achieved using the regular vehicle brake (service brake). Because of braking processes carried out during travel, the brake disk can warm or heat up. This results in the problem, on immobilizing the stationary vehicle with the parking brake, that the coefficient of friction and the expansion of the brake disk change due to the higher temperature. When the brake disk cools after an application of the automatic parking brake, consequently a loss of clamping force of the automatic parking brake can occur. Normally therefore, some time after the application process, a secondary application process is initiated which is calculated and carried out on the basis of information on the brake disk temperature.
If the brake disk temperature determined exceeds a defined value, a not insignificant loss of clamping force of the automatic parking brake is assumed when the brake disk has cooled down after a time period. Then a secondary application process is carried out to compensate for the loss of clamping force. If the brake disk temperature however lies below the predefined temperature value, no secondary application process is carried out because no loss of function is to be expected.
The disadvantage with the conventional method for providing an adequate clamping force is the increasing tendency of many vehicle manufacturers not to use information on brake disk temperature, since this information has many tolerances and therefore is uncertain with reference to an adequate secondary application process.
The object of the present disclosure is therefore to provide a method which guarantees a reliable function of the automatic parking brake even on a loss of clamping force due to a temperature change of the brake disk, and which in addition minimizes the load on components of the automatic parking brake.